Hierarchical modulation for  communication channels in single-carrier frequency division multiple access

ABSTRACT

System(s) and method(s) are provided to transmit simultaneously a first and a second communication channel in a single-carrier waveform format with disparate error rate requirements. First channel and second channel are coded individually to form an alphabet for a first and second constellation. Prior to transmission, bits of information of the first and second channels are modulated with a hierarchical modulation constellation is generated through a combination of a first a second constellation; each constellation is assigned a configurable weight (e.g., a “hierarchic weight”) that is expressed in terms of a configurable energy ratio. The energy ratio determines the resilience of bits associated with the first and second channel. Bit mapping within the first and second constellation provides redundancy to mitigate error rate within each quadrant of the hierarchical constellation. Hierarchical modulation of more than two channels can be accomplished through the same principal of individual coding and constellation composition.

CLAIM OF PRIORITY UNDER 35 U.S.C. §119

This Application for Patent claims the benefit of U.S. ProvisionalApplication Ser. No. 60/942,980 filed on Jun. 8, 2007, and entitled“HIERARCHICAL MODULATION BASED CONTROL CHANNEL FOR SC-FDMA.” The presentApplication is also a continuation application of, and claims priorityto U.S. application Ser. No. 12/135,793, filed Jun. 9, 2008,“HIERARCHICAL MODULATION FOR COMMUNICATION CHANNELS IN SINGLE-CARRIERFREQUENCY DIVISION,” all assigned to the assignee hereof, thedisclosures of which are hereby expressly incorporated herein byreference.

BACKGROUND

I. Field

The following description relates generally to wireless communicationsand, more particularly, to hierarchical modulation of multiplecommunication channels simultaneously conveyed through a single carrier.

II. Background

Wireless communication systems have become a nearly ubiquitous means forcommunication of both voice and data, e.g., video and audio streams,file transfers, web-browsing, and so on. Emergence of new markets forwireless communication, increased complexity of subscriber needs, andcompetition among network operators have driven substantial developmentof wireless technologies at the user equipment and network level. Suchdevelopment has synergistically benefited from a steady development ofcomputing capabilities, or processing power, and miniaturization ofcomputing units.

Wireless communication systems are widely deployed to provide varioustypes of communication content such as voice, data, and so on. Thesesystems may be multiple-access systems capable of supportingcommunication with multiple users by sharing the available systemresources (e.g., bandwidth and transmit power, which typically arefinite, regulated and costly resources). Examples of suchmultiple-access systems include code division multiple access (CDMA)systems; time division multiple access (TDMA) systems; frequencydivision multiple access (FDMA) systems and orthogonal frequencydivision multiple access (OFDMA) systems; and space division multipleaccess (SDMA). Third generation systems like 3rd Generation PartnershipProject 2 Ultra Mobile Broadband (UMB) and 3rd Generation PartnershipProject Long Term Evolution (LTE) systems exploit one or more of thesuch multiple-access paradigms.

In advanced wireless architectures, multiple access paradigms havebenefited from multiple-input multiple-output mode of communication,which effect telecommunication via multiple transceivers in either aserving access terminal or a receiver, or both devices. In addition,multiplexing of traffic and signal generally relies on FrequencyDivision Multiplexing (FDM) which is specified differently in downlinkthan in uplink; while DL utilizes multiple carriers for communication,uplink employs a single carrier (SC) or single-carrier waveform. SC-FDMAprovides substantially all advantages on FDM while mitigatingpeak-to-average ratio (PAPR) fluctuations. Such solution arises at theexpense of a somewhat more complex and multiplexing for UL transport andsignaling channels: Channels are to be multiplexed in contiguous tonesor equally interleaved tones systems exploit single-carrier waveformtransport traffic and control. Furthermore, under specific circumstancestwo channels are required to be transmitted to retain a communication,e.g., a voice or data session, while preserving a subscriber perceivedquality of service, to ensure communication is indeed preserved in suchinstances, various approaches to UL transmission have utilized likejoint coding, time-division multiplexing of information, individualcoding with multiple Zadoff-Chu sequences. Yet those approaches appearto provide far from complete, effective solutions to the problem ofsimultaneous multiple channel transmission.

Therefore there is a need for a transmission formalism for communicationof multiple communication channels with SC-FDMA waveform.

SUMMARY

The following presents a simplified summary in order to provide a basicunderstanding of some aspects of the disclosed embodiments. This summaryis not an extensive overview and is intended to neither identify key orcritical elements nor delineate the scope of such embodiments. Itspurpose is to present some concepts of the described embodiments in asimplified form as a prelude to the more detailed description that ispresented later.

The subject innovation provides system(s) and method(s) to transmitsimultaneously a plurality of communication channels with disparateerror rate requirements in a single-carrier waveform format. A firstchannel and a second channel are coded individually to form an alphabetfor a first and a second constellation. Prior to transmission, P bits (Pa positive integer) of information of the first channel and Q bits (Q apositive integer) of the second channel are modulated with ahierarchical modulation constellation generated through a combination ofthe first a second constellation; each constellation is assigned aconfigurable weight (e.g., a “hierarchic weight”) that is expressed interms of a configurable energy ratio. The energy ratio determines theresilience of bits associated with the first and second channel. Bitmapping within the first and second constellation provides redundancy tomitigate error rate within each quadrant of the hierarchicalconstellation. Hierarchical modulation of more than two channels can beaccomplished through the same principal of individual coding andconstellation composition.

In an aspect of the subject innovation, a method employed in a wirelesscommunication system is described, the method comprising: encoding Pbits (P a positive integer) of information of a first communicationchannel in a first modulation constellation; encoding Q bits (Q apositive integer) of information of a second communication channel in asecond modulation constellation; combining the encoded first modulationconstellation and the encoded second modulation constellation togenerate a hierarchical modulation constellation; and modulating thefirst communication channel and the second communication channel in acommon set of tones with the hierarchical modulation constellation.

In another aspect, the innovation describes a wireless communicationdevice comprising: a processor configured to encode P bits (P a positiveinteger) of information of a first communication channel in a firstmodulation constellation; to encode Q bits (Q a positive integer) ofinformation of a second communication channel in a second modulationconstellation; to assign a first weight to the first encodedconstellation and a second weight to the second encoded constellation togenerate a hierarchical modulation constellation through the combinationof the weighted first encoded constellation and the weighted secondencoded constellation; and to modulate the first communication channeland the second communication channel in a common set of tones with thehierarchical modulation constellation; and a memory coupled to theprocessor.

In yet another aspect, the subject innovation discloses an apparatusthat operates in a wireless communication environment, the apparatuscomprising: means for encoding a first set of bits of information of afirst communication channel in a first modulation constellation; meansfor encoding a second set of bits of information of a secondcommunication channel in a second modulation constellation; means forassigning a first weight to the first encoded constellation and a secondweight to the second encoded constellation to generate a hierarchicalmodulation constellation through the combination of the weighted firstencoded constellation and the weighted second encoded constellation;means for modulating the first communication channel and the secondcommunication channel in a common set of tones with the hierarchicalmodulation constellation; and means for conveying the hierarchicallymodulated first communication channel and second communication channel.

In a further yet aspect, the innovation describes a computer programproduct comprising a computer-readable medium including: code forcausing at least one computer to encode P bits (P a positive integer) ofa first communication channel in a first layer of a modulationconstellation symbol; code for causing at least one computer to encode Qbits (Q a positive integer) of a second communication channel in asecond layer of a modulation constellation symbol; code for causing atleast one computer to generate a hierarchical modulation constellationsymbol through a weighted combination of the encoded first layer of amodulation constellation symbol and the encoded second layer of amodulation constellation; and code for causing at least one computer tomodulate the first communication channel and the second communicationchannel in a common set of tones with a set of hierarchical modulationconstellation symbols.

In another aspect, the subject disclosure describes a method utilized inwireless communications, the method comprising: receiving a firstcommunication channel and a second communication channel that arehierarchically modulated in a composed layer; wherein the composed layerincludes a first layer and a second layer; decoding the first layer; anddecoding the second layer via at least one of a serial decodingsubsequent to decoding the first layer or a parallel decoding concurrentwith decoding the first layer.

In yet another aspect, the subject innovation describes an apparatusthat operates in a wireless communication system, the apparatuscomprising: means for decoding a first layer of information bits of afirst communication channel and a second communication channelhierarchically modulated; and means for decoding a second layer seriallyafter decoding the first layer, wherein decoding the second layerincludes means for cancelling soft symbols decoded in the first layer.

In a further yet aspect, the innovation describes an electronic devicethat operates in a wireless environment, the electronic devicecomprising: a processor configured to decode a first layer ofinformation bits of a first communication channel and a secondcommunication channel hierarchically modulated; and to decode a secondlayer serially after decoding the first layer, wherein decoding thesecond layer includes means for cancelling soft symbols decoded in thefirst layer; an a memory coupled to the processor.

In a still further aspect, the innovation describes a computer programproduct comprising a computer-readable medium including: code forcausing at least one computer to receive a first communication channeland a second communication channel that are hierarchically modulated ina composed layer; wherein the composed layer includes a first layer anda second layer; code for causing at least one computer to decode thefirst layer; and code for causing at least one computer to decode thesecond layer via at least one of a serial decoding subsequent todecoding the first layer or a parallel decoding concurrent with decodingthe first layer, wherein a serial decoding subsequent to decoding thefirst layer includes cancelling soft symbols after decoding the firstlayer.

To the accomplishment of the foregoing and related ends, one or moreembodiments comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative aspectsand are indicative of but a few of the various ways in which theprinciples of the embodiments may be employed. Other advantages andnovel features will become apparent from the following detaileddescription when considered in conjunction with the drawings and thedisclosed embodiments are intended to include all such aspects and theirequivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example multiple access wireless communicationsystem where an access point with multiple antennas simultaneouslycommunicates with various access terminals that operate in SIMO,SU-MIMO, and MU-MIMO mode according to aspects disclosed herein.

FIG. 2 illustrates an example system that exploits hierarchicalmodulation to convey a set of control channels in accordance withaspects described in the subject specification.

FIGS. 3A and 3B illustrate hierarchical modulation of a first and secondchannel in accordance with aspects described in the subjectspecification.

FIGS. 4A through 4C illustrate a hierarchical constellation x that is asuperposition of two QPSK constellations, with information bits of afirst channel mapped on a 2-bit base layer and information bits of asecond channel mapped on an 2-bit enhancement layer in accordance withaspects described herein.

FIGS. 5A-5D illustrate hierarchical constellations that are asuperposition of QPSK constellations for various energy ratios inaddition to a 16QAM constellation.

FIG. 6 illustrates a constellation that provides hierarchicalerasure/error resilience through Gray coding of a first and secondchannels in accordance with aspects described herein.

FIG. 7 is a block diagram of an example embodiment of a transmittersystem and a receiver system in MIMO operation.

FIG. 8 illustrates an example MU-MIMO system.

FIG. 9 presents a flowchart of an example method for hierarchicallymodulating a first and second set of channels according to aspectsdescribed herein.

FIG. 10 is a flowchart of an example method for configuring a set ofhierarchic weights according to aspects of the subject innovationdescribed herein.

FIG. 11 presents a flowchart of an example method for decodinginformation bits of a first and second channels hierarchically modulatedaccording to aspects described herein.

FIG. 12 illustrates a block diagram of an example system that enableshierarchical modulation and utilization thereof in accordance withaspects disclosed in the subject specification.

FIG. 13 illustrates a block diagram of an example system that enables todecode hierarchically modulated channels in accordance with aspectdescribed in the subject specification.

DETAILED DESCRIPTION

Various embodiments are now described with reference to the drawings,wherein like reference numerals are used to refer to like elementsthroughout. In the following description, for purposes of explanation,numerous specific details are set forth in order to provide a thoroughunderstanding of one or more embodiments. It may be evident, however,that such embodiment(s) may be practiced without these specific details.In other instances, well-known structures and devices are shown in blockdiagram form in order to facilitate describing one or more embodiments.

As used in this application, the terms “component,” “module,” “system,”and the like are intended to refer to a computer-related entity, eitherhardware, firmware, a combination of hardware and software, software, orsoftware in execution. For example, a component may be, but is notlimited to being, a process running on a processor, a processor, anobject, an executable, a thread of execution, a program, and/or acomputer. By way of illustration, both an application running on acomputing device and the computing device can be a component. One ormore components can reside within a process and/or thread of executionand a component may be localized on one computer and/or distributedbetween two or more computers. In addition, these components can executefrom various computer readable media having various data structuresstored thereon. The components may communicate by way of local and/orremote processes such as in accordance with a signal having one or moredata packets (e.g., data from one component interacting with anothercomponent in a local system, distributed system, and/or across a networksuch as the Internet with other systems by way of the signal).

Moreover, the term “or” is intended to mean an inclusive “or” ratherthan an exclusive “or”. That is, unless specified otherwise, or clearfrom context, “X employs A or B” is intended to mean any of the naturalinclusive permutations. That is, if X employs A; X employs B; or Xemploys both A and B, then “X employs A or B” is satisfied under any ofthe foregoing instances. In addition, the articles “a” and “an” as usedin this application and the appended claims should generally beconstrued to mean “one or more” unless specified otherwise or clear fromcontext to be directed to a singular form.

Various embodiments are described herein in connection with a wirelessterminal A wireless terminal may refer to a device providing voiceand/or data connectivity to a user. A wireless terminal may be connectedto a computing device such as a laptop computer or desktop computer, orit may be a self-contained device such as a personal digital assistant(PDA). A wireless terminal may also be called a system, a wirelessdevice, a subscriber unit, a subscriber station, a mobile station, amobile terminal, a remote station, an access terminal, a remoteterminal, an access terminal, user terminal, a user agent, a userdevice, a customer premises equipment, or a user equipment, cellulartelephone, personal communication service (PCS) telephone, cordlesstelephone, a session initiation protocol (SIP) telephone, a wirelesslocal loop (WLL) station, a handheld device having wireless connectioncapability, or other processing device connected to a wireless modem.

A base station may refer to a device in an access network thatcommunicates over the air-interface, through one or more sectors, withwireless terminals. The base station may act as a router between thewireless terminal and the rest of the access network, which may includean IP network, by converting received air-interface frames to IPpackets. The base station also coordinates management of attributes forthe air interface. Moreover, various embodiments are described herein inconnection with a base station. A base station may be utilized forcommunicating with mobile device(s) and may also be referred to as anaccess point, Node B, evolved Node B (eNodeB), or some otherterminology.

As it is discussed in greater detail below, system(s) and method(s) aredisclosed that facilitate to transmit simultaneously a plurality ofcommunication channels with disparate error rate requirements in asingle-carrier waveform format. A first channel and a second channel arecoded individually to form an alphabet for a first and a secondconstellation. Prior to transmission, P bits (P a positive integer) ofinformation of the first channel and Q bits (Q a positive integer) ofthe second channel are modulated with a hierarchical modulationconstellation generated through a combination of the first a secondconstellation; each constellation is assigned a configurable weight(e.g., a “hierarchic weight”) that is expressed in terms of aconfigurable energy ratio. The energy ratio determines the resilience ofbits associated with the first and second channel. Bit mapping withinthe first and second constellation provides redundancy to mitigate errorrate within each quadrant of the hierarchical constellation.Hierarchical modulation of more than two channels can be accomplishedthrough the same principal of individual coding and constellationcomposition.

Referring to the drawings, FIG. 1 illustrates a multiple access wirelesscommunication system 100 where an access point 110 with multipleantennas 113-128 simultaneously schedules, and communicates with,various mobile terminals in SIMO, SU-MIMO, and MU-MIMO modes ofoperation according to aspects disclosed herein. The mode of operationis dynamic: access point 110 can reschedule the mode of operation ofeach of terminals 130-160 and 170 ₁-170 ₆. In view of the latter, FIG. 1illustrates a snapshot of communication links between terminals andantennas. As illustrated, such terminals can be stationary or mobileand, dispersed throughout a cell 180. As used herein and generally inthe art, the term “cell” can refer to base station 110 and/or itscoverage geographic area 180 depending on the context in which the termis used. Further, a terminal (e.g., 130-160 and 170 ₁-170 ₆) cancommunicate with any number of base stations (e.g., shown access point110) or no base stations at any given moment. It is noted that terminal130 has a single antenna and therefore it operates in SIMO modesubstantially at all times.

Generally, access point 110 possesses N_(T)≧1 transmit antennas.Antennas in access point 110 (AP) are illustrated in multiple antennagroups, one including 113 and 128, another including 116 and 119, and anadditional including 122 and 125. In FIG. 1, two antennas are shown foreach antenna group, even though more or fewer antennas can be utilizedfor each antenna group. In the snapshot illustrated in FIG. 1, accessterminal 130 (AT) operates in SIMO communication with antennas 125 and122, where antennas 125 and 122 transmit information to access terminal130 over forward link 135 _(FL) and receive information from accessterminal 130 over reverse link 135 _(RL). Mobile terminals 140, 150, and160 each communicate in SU-MIMO mode with antennas 119 and 116. MIMOchannels are formed between each of terminals 140, 150, and 160, andantennas 119 and 116, leading to disparate FLs 145 _(FL), 155 _(FL), 165_(FL), and disparate RLs 145 _(RL), 155 _(RL), 165 _(RL). Additionally,in the snapshot of FIG. 1, a group 185 of terminals 1701-1706 isscheduled in MU-MIMO, having formed multiple MIMO channels between theterminal in the group 185 and antennas 128 and 113 in access point 110.Forward link 175 _(FL) and reverse link RL 175 _(RL) indicate themultiple FLs and RLs existing between terminals 170 ₁-170 ₆ and basestation 110.

In an aspect, system such as LTE and WiMAX can exploit MIMO operationwithin both frequency division duplex (FDD) communication and timedivision duplex (TDD) communication. In FDD communication, links 135_(RL)-175 _(RL) employs different frequency bands from respective links135 _(FL)-175 _(FL). In TDD communication, links 135 _(RL)-175 _(RL) and135 _(FL)-175 _(FL) utilize the same frequency resources; however, suchresources are shared over time among forward link and reverse linkcommunication.

In another aspect, system 100 can utilize one or more multiple-accessschemes, such as CDMA, SDMA, TDMA, FDMA, OFDMA, single-carrier FDMA(SC-FDMA), space division multiple access (SDMA), and/or other suitablemultiple-access schemes. TDMA utilizes time division multiplexing (TDM),wherein transmissions for different terminals 130-160 and 170 ₁-170 ₆are orthogonalized by transmitting in different time intervals. FDMAutilizes frequency division multiplexing (FDM), wherein transmissionsfor different terminals 130-160 and 170 ₁-170 ₆ are orthogonalized bytransmitting in different frequency subcarriers. As an example, TDMA andFDMA systems can also use code division multiplexing (CDM), whereintransmissions for multiple terminals (e.g., 130-160 and 170 ₁-170 ₆) canbe orthogonalized using different orthogonal codes (e.g., Walsh-Hadamardcodes, polyphase codes, Kasami codes) even though such transmissions aresent in the same time interval or frequency subcarrier. OFDMA utilizesorthogonal frequency division Multiplexing (OFDM), and SC-FDMA utilizessingle-carrier FDM. OFDM and SC-FDM can partition the system bandwidthinto multiple orthogonal subcarriers (e.g., tones, bins, . . . ), eachof which can be modulated with data. Typically, modulation symbols aresent in the frequency domain with OFDM and in the time domain withSC-FDM. Additionally and/or alternatively, the system bandwidth can bedivided into one or more frequency carriers, each of which can containone or more subcarriers. While pilot design and scheduling of SIMO,SU-MIMO, and MU-MIMO user described herein are generally described foran OFDMA system, it should be appreciated that the techniques disclosedherein can similarly be applied to substantially any wirelesscommunication system operating in multiple access.

In a further aspect, base stations 110 and terminals 120 in system 100can communicate data using one or more data channels and signaling usingone or more control channels. Data channels utilized by system 100 canbe assigned to active terminals 120 such that each data channel is usedby only one terminal at any given time. Alternatively, data channels canbe assigned to multiple terminals 120, which can be superimposed ororthogonally scheduled on a data channel. To conserve system resources,control channels utilized by system 100 can also be shared amongmultiple terminals 120 using, for example, code division multiplexing.In one example, data channels orthogonally multiplexed only in frequencyand time (e.g., data channels not multiplexed using CDM) can be lesssusceptible to loss in orthogonality due to channel conditions andreceiver imperfections than corresponding control channels.

Each group of antennas and/or the area in which they are designed tocommunicate is often referred to as a sector of the access point. Asector can be an entire cell 180, as illustrated in FIG. 1, or a smallerregion. Typically, when sectorized, a cell (e.g., 180) includes a fewsectors (not shown) covered by a single access point, such as 110. Itshould be appreciated that the various aspects disclosed herein can beused in a system having sectorized and/or unsectorized cells. Further,it should be appreciated that all suitable wireless communicationnetworks having any number of sectorized and/or unsectorized cells areintended to fall within the scope of the hereto appended claims. Forsimplicity, the term “base station” as used herein can refer both to astation that serves a sector as well as a station that serves a cell.While the following description generally relates to a system in whicheach terminal communicates with one serving access point (e.g., 110) forsimplicity, it should further be appreciated that terminals cancommunicate with substantially any number of serving access points.

In communication over forward links 135 _(FL)-175 _(FL), thetransmitting antennas of access point 110 can utilize beamforming (e.g.,to effect SDMA communication) in order to improve the signal-to-noiseratio of forward links for the different access terminals 130-160 and170 ₁-170 ₆. Also, an access point using beamforming to transmit toaccess terminals scattered randomly through its coverage causes lessinterference to access terminals in neighboring cells than an accesspoint transmitting through a single antenna to all its access terminals.

It is noted that base station 110 can communicate via backhaul networkwith other base stations (not shown) that serve other cells (not shown)in the cellular network of which cell 180 is part of Such communicationis a point-to-point communication effected over the cellular networkbackbone, which can employ of T-carrier/E-carrier links (e.g., T1/E1lines), as well as packet-based intern& protocol (IP).

FIG. 2 illustrates an example system 200 that exploits hierarchicalmodulation to convey a set physical layer channels. Channels can betraffic channels or control channels (e.g., channel quality indication(CQI), rank indication (RI), acknowledge/not-acknowledge (ACK/NACK),precoding matrix indicator (PMI)). Disparate channels, either transportor control channels, are generally conveyed with disparate formats. Suchformats typically include disparate conveyed bits based on mode ofoperation; for instance ACK in LTE conveys 1 bit of information in SIMO,whereas it conveys 2 bits in SU-MIMO mode, while CQI conveys 5 bits ofinformation in SIMO and 8 bits of information in SDMA and SU-MIMO. ForLTE, it should also be appreciated that in uplink communication oftraffic or control channel a single-carrier FDMA waveform is utilizedfor communication.

In example system 210, a novel hierarchical modulation is provided.Hierarchical modulation affords simultaneous communication of disparatechannels, e.g., CHJ 228 and CHK 232, within a single-carrier FDMAformat. To at least that end, hierarchical modulation component 214modulates a set of control channels like Channel J (CHJ) 228 and ChannelK (CHK) 232 in accordance with a modulation constellation χ that is ahierarchic superposition of constellations χ_(B) and χ_(E):

χ=α_(B)χ_(B)+α_(E)χ_(E),   (1)

wherein α_(B) and α_(E) are hierarchic weights of the hierarchicalconstellation χ, and satisfy α_(B) ²+α_(E) ²=1. The hierarchy ofconstellations χ_(B) and χ_(E) is dictated by the relative magnitude ofthe hierarchic weights, such relative magnitude can be determinedthrough an “energy ratio” ε which can be defined as:

$\begin{matrix}{ɛ = {\frac{\alpha_{B}^{2}}{\alpha_{E}^{2}}.}} & (2)\end{matrix}$

Hierarchic weights can be expressed in terms of the energy ratio ε asfollows.

$\begin{matrix}\left\{ \begin{matrix}{\alpha_{B} = \sqrt{\frac{ɛ}{1 + ɛ}}} \\{\alpha_{E} = {\sqrt{\frac{ɛ}{1 + ɛ}}.}}\end{matrix} \right. & (3)\end{matrix}$

The leading hierarchic weight, e.g., as defined in Eq. (3), determinesthe constellation that is afforded a stronger protection for encoding,while the constellation associated with the remaining weight afforded aweaker protection. It should be appreciated that herein the term“protection” refers to erasure mitigation. Nearly-symmetric error ratecan be accomplished through small (O(1)) energy ratios.

Hierarchical modulation component 214 relies on mapping component 215 tomap information bits associated with CHJ 228 and CHK 232 toconstellations χ_(A) and χ_(B), respectively. Such structure isillustrated below (see FIG. 3A). Additionally, hierarchical modulationcomponent 214 includes a multiplexing (MUX) component 216 thatmultiplexes a set of points in a hierarchical constellation c, whichincludes bits of information for both channel CHJ 228 and CHK 232,within a granted (by Node B 240) set of tones (e.g., in LTE the set oftones can be an isochronous slice of one or more resource blocks (RBs),each RB includes 12 subcarriers per OFDM symbol).

Hierarchical modulation component 214 conveys the multiplexed,hierarchically modulated symbols for channels CHJ 228 and CHK 232.

A set of constellations χ, χ_(A), and χ_(B), can be stored inconstellation store 226. It should be appreciated that constellationstorage 226 can also be a part of memory 222. Constellations χ_(B) andχ_(E) possess, respectively, alphabets A_(B) and A_(E), such alphabetscomprise codewords N_(B) and N_(E) which afford encoding log₂N_(λ) bits(λ=B, E). It is to be noted that constellation χ_(λ) can besubstantially any constellation and need not be the same as otherconstellation that enters the hierarchic constellation χ; for instance,constellation χ_(λ) can be a constellation associated with a binaryphase-shift keying modulation (BPSK), a quadrature phase-shift keying(QPSK) modulation, a quadrature amplitude modulation (QAM), M-ary QAM(M-QAM), and so on. It is to be noted that depending wirelesscommunication technology (e.g., LTE, UMB) utilized for communication inexample system 200, a specific set of modulations, and thusconstellations, may be available. For example, in LTE, QPSK, 16-QAM, or64-QAM is available for modulation of the Physical Uplink ControlChannel (PUCCH).

In an aspect, configuration component 222 can adjust energy ratios, orhierarchic weight(s) 224, to establish a specific erasure/error rate forCHJ 228 and CHK 232. For instance, an energy ratio can be adjusted on aper-terminal basis, which can include adjustments on (i) a per-flowbasis; for instance, specific executed applications like voice, video-and music-streaming are sensitive to latency and jitter, thus an energyratio ε can be configured to ensure mitigation of latency and jitter;and (ii) a per-equipment mode of operation, such as SISO, SIMO, SU-MIMO,and MU-MIMO. In an aspect, configuration component can adjust energyratio(s) or hierarchic weight(s) 224, upon receiving specific signaling225 such as an express indication (e.g., an E-bit codeword with E apositive integer) to adjust ε, a scheduling grant, an other-sectorinterference indication, a handover request, uplink signal strength, andso on. Also, specific characteristics of received data 225 can triggeran adjustment of energy ratio or hierarchic weight(s) 224; for example,statistics of received data packets, packet format, and so on.

It should be appreciated that T-tier hierarchies, e.g., T hierarchicallymodulated control channels (T a positive integer greater than 2), arewithin the scope of the subject innovation. While T-tier hierarchies mayintroduce additional computational and signaling complexity, ahierarchical modulation of T channels can provide various advantages.For instance, multiple ACK/NACK channels can be conveyed in response todisparate flows with disparate quality of service restrictions, orpacket formats.

In example system 200, hierarchical modulation component 210 resides inaccess terminal 210; however, it should be appreciated that thehierarchical modulation component 210 can reside in substantially anytransmitter that conveys control channels.

Hierarchically modulated channels can be received by Node B 240. Adetection component 214 decodes the received hierarchically modulatedCHJ 228 encoded in a base layer, and CHK 232 encoded in an enhancedlayer. Base layer decoding can proceeds through computation oflog-likelihood ratios (LLRs) from all codewords, or constellationpoints, in a hierarchical constellation utilized for modulation.Enhanced layer decoding can be implemented in serial or parallel withbase layer decoding. Serial decoding of enhanced layer entails (i)detection of base layer and cancellation of decoded base layer from softsymbols, and (ii) computation of LLRs from enhancement layerconstellation codewords. It should be appreciated that in serialdecoding, the more robust channel (e.g., low-error rate) can be decodedfirst; namely, the channel encoded in the base layer is decoded first.Due to the hierarchical decoding, once base-layer information bits aredecoded, information on constellation quadrant is straightforwardlyextracted. Parallel decoding relies on LLR computation from allcodewords in hierarchical constellation.

Detection mechanisms exploited by detection component 244 can include amaximum likelihood (ML) estimator, a minimum mean square equalizer(MMSE), a zero forcing (ZF) filter, or maximal ratio combining (MRC)filter. Such detection components can incorporate additionally asuccessive interference cancellation (SIC) component. Moreover,detection component 244 can perform serial-to-parallel splitting of areceived data stream, cyclic prefix removal, and inverse/direct Fourierand/or Hadamard transformation(s) in order to extract received symbols.

It should be appreciated that M-tier hierarchies, e.g., M hierarchicallymodulated control channels (M a positive integer greater than 2), can bedecoded either in serial or parallel. It is noted that processor 252 isconfigured to perform at least a portion of the actions, e.g.,computations, and logic associated with functionality and operation ofdetection component 244.

In addition to detection component 244, Node B 240 includes aconfiguration component 248 that can establish hierarchic weight(s) 224and convey such weight, or an indication thereof (e.g., an L-bitcodeword to be used in conjunction with a lookup table in accessterminal 210 in order to set a hierarchic weight), in a data or controlcommunication 258. Configuration component 248 can adjust hierarchicweight(s) 224 based at least in part on quality of service (QoS), e.g.,specific erasure/error rates for CHJ 228 and CHK 232. For example, it isto be appreciated that error rates in control channels like CQI and ACKcan be critical to retaining QoS metrics such as subscriber agreedservice; for example, guaranteed bit rate (GBR), average bit rate (ABR),and minimum bit rate (MINBR); block error rate (BLER), packet error rate(PER), bit error rate (BER); and peak data rate (PDR). It is to be notedthat configuration component 248 can adjust hierarchic weight(s) 224 ona per-subscriber basis since disparate subscribers can have access todisparate rate levels; e.g., enterprise subscribers can have access tohard QoS that ensures a specific GBR rather than a MINBR. Configurationcomponent 248 can also configure hierarchic weight(s) 224 on a per-flowbasis, wherein disparate applications executed by a subscriber areserviced within different agreed rates, and thus different quality,resilience, or integrity of control (error rate in CQI and ACK) can bewarranted. For instance, voice communication, ecommerce, or wirelessbanking can depend critically on accurate CQI and ACK, whereasapplication such as web browsing, or file transfer can tolerate ansignificantly asymmetric quality (e.g., erasure rate) among CQI and ACK.

Configuration component can configure energy ratios or hierarchicweights in accordance with changes in operation mode of mobilestation(s). For example, configuration component 248 can adjust eitheradjust hierarchic weight(s) 224, or convey an indication for adjustmentthereof, as a response to scheduled changes in mode of operation (e.g.,SISO, SIMO, SU-MIMO, or MU-MIMO) of a mobile station. Such modes ofoperation, and their afforded capacity, depend to substantiallydifferent extents on access to channel state information (e.g., CQI andACK, which reflect channel strength conditions and packet transmissionefficiency) at a served terminal

Furthermore, user equipment generally possesses a specific set oftechnical capabilities like number of antennas, multi-mode (e.g.,multiple system bandwidth operation; multiple telecommunicationtechnology such as WCDMA, HSDPA; or telecommunication services like GPS)or single-mode chipsets, battery resources (e.g., long dischargecharacteristic time, solar-power assisted, . . . ), and so on, which canresult in substantially different operation performance on availabilityor generation of simultaneous control channels such as CQI, or ACK/NACK.For example, generation and transmission of highly asymmetric qualityCHJ 228/CHK 232 can result in excessive overhead or unwarranted batterinefficiency; thus, configuration component can optimize a relativequality for CHJ 228 and CHK 232 through hierarchic weight(s) 224.

In an aspect, in example system 200, configuration components 217 and248 can rely upon an intelligent component (not shown) to autonomouslyfind, adapt, or optimize values of energy ratios or hierarchic weights224 in accordance with aspects described above. To that and other endsrelated to adaptation or optimization in other portions of the subjectdescription associated with additional functionalities of the subjectinnovation, the term “intelligence” refers to the ability to reason ordraw conclusions about, e.g., infer, the current or future state of asystem based on existing information about the system. Artificialintelligence can be employed to identify a specific context or action,or generate a probability distribution of specific states of a systemwithout human intervention. Artificial intelligence relies on applyingadvanced mathematical algorithms—e.g., decision trees, neural networks,regression analysis, cluster analysis such as primary componentanalysis, spectral analysis like wavelet decomposition, geneticalgorithms, and reinforced learning—to a set of available data(information) on the wireless communication system (e.g., service cell180).

In particular, to the accomplishment of the various automated aspectsdescribed above and other automated aspects relevant to the subjectinnovation described herein, an intelligent component (not shown) canemploy one of numerous methodologies for learning from data and thendrawing inferences from the models so constructed, e.g., Hidden MarkovModels (HMMs) and related prototypical dependency models, more generalprobabilistic graphical models, such as Bayesian networks, e.g., createdby structure search using a Bayesian model score or approximation,linear classifiers, such as support vector machines (SVMs), non-linearclassifiers, such as methods referred to as “neural network”methodologies, fuzzy logic methodologies, and other approaches thatperform data fusion, etc.

It is to be appreciated that in example system 200, detection component244 resides in Node B 210, even though this detection component canreside in substantially any receiver that operates in a wirelessenvironment and receives control signaling.

It is to be noted that processors 252 and 218 are configured to performat least a portion of the functional actions, e.g., computations,necessary to implement the functionality described herein ofsubstantially any component in Node B 240 and access terminal 210,respectively. Memories 256 and 222 can retain data structures, codeinstructions, algorithms, and the like, that can be employed,respectively, by processors 225 and 218 when conferring Node B 240 oraccess terminal 210 its functionality.

FIGS. 3A and 3B illustrate hierarchical modulation of channels CHJ 228and CHK 232. FIG. 3A is a diagram of a base layer 310 that comprises Pbits of information and an enhanced layer 320 which includes Q bits ofinformation, respectively. Bits in the base layer and enhancement layerare coded independently. Modulation of P+Q bits is based on ahierarchical constellation c 330, which comprises two constellations,one constellation χ_(B) 336 with 2^(Q) codewords and a secondconstellation χ_(E) 338 with 2^(P) codewords. Mapping of informationbits to the alphabet of χ330 is performed in accordance with base layerand enhancement layer, wherein the first P bits modulated in codeword,or constellation point, correspond to the first channel CHJ 228, and thetrailing Q bits correspond in turn to the second channel CHK 232.

FIG. 3B is a diagram that displays illustrative hierarchic weights α_(B)358 and α_(E) 362. As discussed, above the hierarchic weights define anenergy ratio

$ɛ = \frac{\alpha_{B}^{2}}{\alpha_{E}^{2}}$

354 which determines quantifies the two-tier hierarchy among χ_(E) 336and χ_(E) 338. A larger hierarchic weight confers a larger degree ofprotection to the modulated bits of information associated with theconstellation that carries the larger weight. To complement protection,bit mapping is to be hierarchical in the sense that bits in a base layerare mapped to the first P bits in a constellation codeword, and bits inthe enhancement layer are mapped to remaining Q bits.

FIG. 4 illustrates an example hierarchical constellation χ that is asuperposition of two QPSK constellations, the bit mapping in χ resultsfrom mapping 2 bits of information for base layer 310 and 2 bits ofinformation for enhancement layer 320. First constellation χ_(B) 410 anda second constellation χ_(E) 420 map 2 bits of information associatedwith CHJ 228 (e.g., ACK channel) and CHK 232 (e.g., CQI channel),respectively. Each quadrant in resulting hierarchical constellation c430 is associated with a same pair of information bits for the baselayer, e.g., ‘00’ in first quadrant (I,Q>0), whereas disparateconstellation points in each quadrant carry disparate pair ofinformation bits for enhancement layer. It is to be noted thatconstellations 410 and 420 are encoded individually and such encodingremains the same regardless of the energy ratio among χ_(B) 410 andχ_(E) 420. The redundancy of base layer bits in each quadrant providesincreased relative protection with respect to information bits ofenhancement layer.

FIGS. 5A through 5D illustrate hierarchical constellations {χ_(i), χ₂,χ₃, χ₄} that are a superposition of QPSK constellations for energyratios {ε₁, ε₂, ε₃, ε₄}, respectively. For reference a 16-QAMconstellation is also illustrated in conjunction with each χ_(μ) (μ=1, .. . , 4). As the energy ratio is increased, hierarchical constellationsχ_(μ) display more pronounced clusters of codewords, or constellationpoints. Therefore, communication errors in bits associated with a baselayer (e.g., CHJ 228) encoded with codewords in disparate clusters aresubstantially mitigated, whereas bit error rate in an enhanced layer(e.g., CHK 232) is increased. Adjusting energy ratio provides amechanism to adjust a specific erasure rate for base-layer bits;however, such adjustment of base-layer protection is attained at theexpense of enhanced-layer bit error rate. Thus, a tradeoff can beaccomplished based on various communication conditions that warrantspecific erasure for a channel mapped to base layer and a channel mappedto enhanced layer. As illustrated in FIG. 5A, hierarchical constellationχ₁, which has ε=4, is nearly as symmetric as 16QAM. However, in view ofthe coherent nature of hierarchical constellation χ₁ 500, and thatbase-layer bits are the first encoded information bits in thehierarchical constellation codewords, codewords in each quadrant remainto convey the same information bits for base layer and thus base layeris slightly more resilient than its enhanced layer counterpart. FIG. 5Breveals that an increase of energy ratio from ε=4 to ε=9 results in a χ₂525 that presents clearly clustered groups of four codewords in eachquadrant. The clustering increases a distinction among constellationpoints associated with disparate base-layer information bits, thussubstantially more protection is afforded to such layer at the expenseof resilience of enhanced layer information bits, which are mapped intocodewords within a same quadrant. FIG. 5C displays a further pronouncedclustering in each quadrant for χ₃ 550, defined through an energy ratioε=19; χ₃ 550 affords a greater protection to base-layer bits at theexpense of lesser protection to enhanced-layer bits. FIG. 5D displays ayet further pronounced clustering of constellation points for χ₄ 575,which results from a superposition with ε=25, the clustering furtherincreases integrity of base-layer bits of information at expense ofresilience of enhanced-layer bits.

FIG. 6 illustrates a constellation that provides erasure/errorresilience through Gray coding as an alternative or in addition tohierarchical superposition. It should be appreciated that Gray mappingwith 16-QAM reduces complexity through reduction to a singleconstellation, or alphabet. As discussed above, 16-QAM with Gray mappingis a quasi-χ₁ (e.g., ε=4) hierarchical constellation with Gray coding,in which information bit mapping relies on distinction among mostsignificant bits (MSBs) and least significant bits (LSBs). It should beappreciated that protection afforded to a first channel (e.g., CHJ 228)and a second channel (e.g., CHK 232) is substantially the same.

FIG. 7 is a block diagram 700 of an embodiment of a transmitter system710 (such as Node B 240) and a receiver system 750 (e.g., accessterminal 210) in a multiple-input multiple-output (MIMO) system that canprovide for cell (or sector) communication in a wireless environment inaccordance with one or more aspects set forth herein. At the transmittersystem 710, traffic data for a number of data streams can be providedfrom a data source 712 to transmit (TX) data processor 714. In anembodiment, each data stream is transmitted over a respective transmitantenna. TX data processor 714 formats, codes, and interleaves thetraffic data for each data stream based on a particular coding schemeselected for that data stream to provide coded data. The coded data foreach data stream may be multiplexed with pilot data using OFDMtechniques. The pilot data is typically a known data pattern that isprocessed in a known manner and can be used at the receiver system toestimate the channel response. The multiplexed pilot and coded data foreach data stream is then modulated (e.g., symbol mapped) based on aparticular modulation scheme (e.g., binary phase-shift keying (BPSK),quadrature phase-shift keying (QPSK), multiple phase-shift keying(M-PSK), or m-order quadrature amplitude modulation (M-QAM)) selectedfor that data stream to provide modulation symbols. The data rate,coding, and modulation for each data stream may be determined byinstructions executed by processor 730, the instructions as well as thedata may be stored in memory 732.

The modulation symbols for all data streams are then provided to a TXMIMO processor 720, which may further process the modulation symbols(e.g., OFDM). TX MIMO processor 720 then provides N_(T) modulationsymbol streams to N_(T) transceivers (TMTR/RCVR) 722 _(A) through 722_(T). In certain embodiments, TX MIMO processor 720 applies beamformingweights (or precoding) to the symbols of the data streams and to theantenna from which the symbol is being transmitted. Each transceiver 722receives and processes a respective symbol stream to provide one or moreanalog signals, and further conditions (e.g., amplifies, filters, andupconverts) the analog signals to provide a modulated signal suitablefor transmission over the MIMO channel. N_(T) modulated signals fromtransceivers 722 _(A) through 722 _(T) are then transmitted from N_(T)antennas 724 ₁ through 724 _(T), respectively. At receiver system 750,the transmitted modulated signals are received by N_(R) antennas 752 ₁through 752 _(R) and the received signal from each antenna 752 isprovided to a respective transceiver (RCVR/TMTR) 754 _(A) through 754_(R). Each transceiver 754 ₁-654 _(R) conditions (e.g., filters,amplifies, and downconverts) a respective received signal, digitizes theconditioned signal to provide samples, and further processes the samplesto provide a corresponding “received” symbol stream.

An RX data processor 760 then receives and processes the N_(R) receivedsymbol streams from N_(R) transceivers 754 ₁-654 _(R) based on aparticular receiver processing technique to provide N_(T) “detected”symbol streams. The RX data processor 760 then demodulates,deinterleaves, and decodes each detected symbol stream to recover thetraffic data for the data stream. The processing by RX data processor760 is complementary to that performed by TX MIMO processor 720 and TXdata processor 714 at transmitter system 710. A processor 770periodically determines which pre-coding matrix to use, such a matrixcan be stored in memory 772. Processor 770 formulates a reverse linkmessage comprising a matrix index portion and a rank value portion.Memory 772 may store instructions that when executed by processor 770result in formulating the reverse link message. The uplink message maycomprise various types of information regarding the communication linkor the received data stream, or a combination thereof. As an example,such information can comprise channel quality indication(s), an offsetfor adjusting a scheduled resource, and/or sounding reference signalsfor link (or channel) estimation. The uplink message is then processedby a TX data processor 738, which also receives traffic data for anumber of data streams from a data source 736, modulated by a modulator780, conditioned by transceiver 754 _(A) through 754 _(R), andtransmitted back to transmitter system 710. It should be appreciatedthat the uplink message can include multiple channels transmittedsimultaneously, such scenario is handled, at least in part, byhierarchical modulation component 781 which can operate according toaspects described hereinbefore.

At transmitter system 710, the modulated signals from receiver system750 are received by antennas 724 ₁-724 _(T), conditioned by transceivers722 _(A)-722 _(T), demodulated by a demodulator 740, and processed by aRX data processor 742 to extract the reserve link message transmitted bythe receiver system 750. Processor 730 then determines which pre-codingmatrix to use for determining the beamforming weights and processes theextracted message.

When a receiver 750 can be dynamically scheduled to operate in SIMO,SU-MIMO, and MU-MIMO, disparate hierarchical modulation can be warrantedwhen transmitting two channels simultaneously within a single-carrierwaveform. Adjustment to hierarchic weights associated with hierarchicalconstellation(s) can be effected in response to changes in scheduledmode of operation. Next, communication in these modes of operation isdescribed. It is noted that in SIMO mode a single antenna at thereceiver (N_(R)=1) is employed for communication; therefore, SIMOoperation can be interpreted as a special case of SU-MIMO. Single-userMIMO mode of operation corresponds to the case in which a singlereceiver system 750 communicates with transmitter system 710, aspreviously illustrated FIG. 7 and according to the operation describedin connection therewith. In such a system, the N_(T) transmitters 724₁-724 _(T) (also known as TX antennas) and N_(R) receivers 752 ₁-752_(R) (also known as RX antennas) form a MIMO matrix channel (e.g.,Rayleigh channel, or Gaussian channel, with slow or fast fading) forwireless communication. As mentioned above, the SU-MIMO channel isdescribed by a N_(R)×N_(T) matrix of random complex numbers. The rank ofthe channel equals the algebraic rank of the N_(R)×N_(T) matrix, whichin terms of space-time, or space-frequency coding, the rank equals thenumber N_(V)≦min{N_(T), N_(R)} of independent data streams (or layers)that can be sent over the SU-MIMO channel without inflictinginter-stream interference.

In one aspect, in SU-MIMO mode, transmitted/received symbols with OFDM,at tone ω, can be modeled by:

y(ω)= H (ω)c(ω)+n(ω).   (4)

Here, y(ω) is the received data stream and is a N_(R)×1 vector, H(ω) isthe channel response N_(R)×N_(T) matrix at tone ω (e.g., the Fouriertransform of the time-dependent channel response matrix h), c(ω) is anN_(T)×1 output symbol vector, and n(ω) is an N_(R)×1 noise vector (e.g.,additive white Gaussian noise). Precoding can convert a N_(V)×1 layervector to N_(T)×1 precoding output vector. N_(V) is the actual number ofdata streams (layers) transmitted by transmitter 710, and N_(V) can bescheduled at the discretion of the transmitter (e.g., transmitter 710,Node B 250, or access point 110) based at least in part on channelconditions (e.g., reported CQI) and the rank reported (e.g., through RI)in a scheduling request by a terminal (e.g., receiver 750). It should beappreciated that in an instance in which CQI and RI are to be conveyedsimultaneously, hierarchical simulation can be exploited to ensureadequate report quality (e.g., error rate) of each of the channels. Itshould be appreciated that c(ω) is the result of at least onemultiplexing scheme, and at least one pre-coding (or beamforming) schemeapplied by the transmitter. Additionally, c(ω) is convoluted with apower gain matrix, which determines the amount of power transmitter 710allocates to transmit each data stream N_(V). It should be appreciatedthat such a power gain matrix can be a resource that is assigned to aterminal (e.g., access terminal 220, receiver 750, or UE 140), and itcan be controlled through power adjustment offsets.

As mentioned above, according to an aspect, MU-MIMO operation of a setof terminals (e.g., mobiles 170 ₁-170 ₆) is within the scope of thesubject innovation. Moreover, scheduled MU-MIMO terminals operatejointly with SU-MIMO terminals and SIMO terminals. FIG. 8 illustrates anexample multiple-user MIMO system 800 in which three ATs 750 _(P), 750_(U), and 750 _(S), embodied in receivers substantially the same asreceiver 750, communicate with transmitter 710, which embodies a Node B.It should be appreciated that operation of system 700 is representativeof operation of substantially any group (e.g., 185) of wireless devices,such as terminals 170 ₁-170 ₆, scheduled in MU-MIMO operation within aservice cell by a centralized scheduler residing in a serving accesspoint (e.g., 110 or 250). As mentioned above, transmitter 710 has N_(T)TX antennas 724 ₁-724 _(T), and each of the ATs has multiple RXantennas; namely, AT_(P) has N_(P) antennas 752 ₁-652 _(P), AP_(U) hasN_(U) antennas 752 ₁-752 _(U), and AP_(S) has N_(S) antennas 752 ₁-752_(S). Communication between terminals and the access point is effectedthrough uplinks 815 _(P), 815 _(U), and 815 _(S). Similarly, downlinks810 _(P), 810 _(U), and 810 _(S) facilitate communication between Node B710 and terminals AT_(P), AT_(U), and AT_(S), respectively.Additionally, communication between each terminal and base station isimplemented in substantially the same manner, through substantially thesame components, as illustrated in FIG. 8 and its correspondingdescription.

Terminals can be located in substantially different locations within thecell serviced by access point 710 (e.g., cell 180), therefore each userequipment 750 _(P), 750 _(U), and 750 _(S) has its own MIMO matrixchannel h_(α) and response matrix H_(α) (α=P, U, and S), with its ownrank (or, equivalently, singular value decomposition). Intra-cellinterference can be present due to the plurality of users present in thecell serviced by the base station 710. Such interference can affect CQIand ACK, as well as substantially all traffic and control channels,reported by each of terminals 750 _(P), 750 _(U), and 750 _(S).Accordingly, Node B 710 can adjust a set of hierarchical constellationsutilized by terminals 750 _(P), 750 _(U), and 750 _(S) in order toensure satisfactory accuracy in CQI and ACK reports when conveyedsimultaneously.

Although illustrated with three terminals in FIG. 8, it should beappreciated that a MU-MIMO system can comprise any number of terminals,each of such terminals indicated below with an index k. In accordancewith various aspects, each of the access terminals 750 _(P), 750 _(U),and 750 _(S) can report CQI and ACK hierarchically modulated to Node B710. In addition, each of such terminals can transmit to Node B 710sounding reference signals from each antenna in the set of antennasemployed for communication. Node B 710 can dynamically re-schedule eachof terminals 750 _(P), 750 _(U), and 750 _(S) in a disparate mode ofoperation such as SU-MIMO or SIMO.

In one aspect, transmitted/received symbols with OFDM, at tone ω and foruser k, can be modeled by:

y _(k)(ω)= H _(k)(ω)+ H _(k)(ω)Σ′c _(m)(ω)+n _(k)(ω).   (5)

Here, symbols have the same meaning as in Eq. (1). It should beappreciated that due to multi-user diversity, other-user interference inthe signal received by user k is modeled with the second term in theleft-hand side of Eq. (2). The prime (′) symbol indicates thattransmitted symbol vector c_(k) is excluded from the summation. Theterms in the series represent reception by user k (through its channelresponse H _(k)) of symbols transmitted by a transmitter (e.g., accesspoint 210) to the other users in the cell.

In view of the example systems shown and described above, methodologiesthat may be implemented in accordance with the disclosed subject matter,will be better appreciated with reference to the flowcharts of FIGS. 9,10 and 11. While, for purposes of simplicity of explanation, themethodologies are shown and described as a series of blocks, it is to beunderstood and appreciated that the claimed subject matter is notlimited by the number or order of blocks, as some blocks may occur indifferent orders and/or concurrently with other blocks from what isdepicted and described herein. Moreover, not all illustrated blocks maybe required to implement the methodologies described hereinafter. It isto be appreciated that the functionality associated with the blocks maybe implemented by software, hardware, a combination thereof or any othersuitable means (e.g., device, system, process, component, . . . ).Additionally, it should be further appreciated that the methodologiesdisclosed hereinafter and throughout this specification are capable ofbeing stored on an article of manufacture to facilitate transporting andtransferring such methodologies to various devices. It should beappreciated that a methodology described herein could alternatively berepresented as a series of interrelated states or events, such as in astate diagram. In addition, a methodology derived from a combination ofat least portions of disparate methodologies described herein may berepresented as an interaction diagram or a call flow rather than throughflowchart(s).

FIG. 9 presents a flowchart of an example method 900 for hierarchicallymodulating a first and second set of channels. In an aspect the examplemethod 900 can be utilized by a transmitter in a wireless environmentthat communicates information in a single-carrier waveform, like an LTEmobile station conveying information in uplink. It should be appreciatedthat example method 900 can be exploited in substantially any wirelesscommunication technology that relies on frequency division multiplexingsuch as ultra-mobile broadband (UMB) or worldwide interoperability formicrowave access (WiMAX).

At act 910, P bits of information of a first channel are encoded in afirst modulation constellation. The first channel can be a data channel(PUSCH) or a control channel (PUCCH). The first modulation constellationcan be substantially any modulation constellation including M-ary QAM,and on. At act 920, Q bits of information of a second channel areencoded in a second modulation constellation. The second channel can bea data channel (PUSCH) or a control channel (PUCCH). The firstmodulation constellation can be substantially any modulationconstellation including M-ary QAM, and on. At act 930, a hierarchicalmodulation constellation is generated through a weighted combination ofthe first and second modulation constellations. In an aspect, theweights are dictated by a configurable energy ratio ε (see Eq. (3) andFIGS. 3A-3B). The energy ratio facilitates, at least partially,determining a relative degree of erasure of information bits encoded inthe weighted, combined modulation constellation. At act 940, the firstand second channels are modulated with the hierarchical modulationconstellation. At act 950, the hierarchically modulated first and secondchannels are conveyed. In an aspect, the first and second channels areconveyed in a single carrier. It is to be noted that modulation ofinformation bits of first and second channel through hierarchicalmodulation constellation ensures that communication can be effectedthrough a single carrier.

FIG. 10 is a flowchart of an example method for configuring a set ofhierarchic weights according to aspects of the subject innovationdescribed herein. At act 1010, a set of hierarchic weights (e.g., α_(B)and α_(E)), or energy ratios, is configured. Such configuration can beimplemented on a per-terminal basis, a per-flow basis, or aper-subscriber basis. Hierarchic weights can be determined based atleast in part on (1) QoS specifications such as GBR, ABR, BER, PER,BLER, traffic handling priority which typically determines schedulingpriorities—generally dictated by channel quality indicators in a servedmobile station; and (2) user equipment capabilities or mode ofoperation. It should be appreciated that other sources, metrics, orparameters can also be utilized to determine hierarchic weights, orenergy ratios. In an aspect, configuration of hierarchic weights orenergy ratios can be autonomously and dynamically adjusted in responseto changes in aforementioned sources (1) or (2), like changes inscheduled mode of operation of a device; e.g., a mobile station switchesfrom SIMO operation to MIMO operation. At act 1020, a first weight inthe configured set of hierarchic weights is assigned to a first encodedconstellation and a second weight in the configured set of hierarchicweights is assigned to the second encoded constellation. At act 1030, aset of configured hierarchic weights is retained. In an aspect,hierarchic weights can be stored in a memory on the network deviceconfiguring the hierarchic weights. At act 1030, a configured hierarchicweight is conveyed.

FIG. 11 presents a flowchart of an example method for decodinginformation bits of a first and second channels hierarchicallymodulated. At act 1110, a first and second channels that arehierarchically modulated in a first and a second layers are received(see FIGS. 3A and 3B for an illustration of a layered coding structure).The first and second channels can be substantially any traffic orcontrol channels in a system that effects a wireless communication. Atact 1120, the first layer associated with information bits of the firstchannel is decoded. It is to be noted that first layer do not carryinformation bits of second channel. At act 1130, the second layerassociated with information bits in the second channel is decoded. Inview of the layered coding of the received bit stream, e.g., first andsecond channels modulated hierarchically, the second layer can bedecoded through (i) parallel decoding with the first layer, wherein forexample LLRs are computed for all constellation points; or (ii) serialdecoding in which exploits knowledge of the bit mapping structure:Decoded bits from base layer are cancelled from soft symbols and LLRsare computed from enhancement layer constellation points.

Next, systems that can enable aspects of the disclosed subject matterare described in connection with FIGS. 12 and 13. Such systems caninclude functional blocks, which can be functional blocks that representfunctions implemented by a processor or an electronic machine, software,or combination thereof (e.g., firmware).

FIG. 12 illustrates a block diagram of an example system 1200 thatenables hierarchical modulation and utilization thereof in accordancewith aspects disclosed in the subject specification. System 1200 canreside, at least partially, within a mobile (e.g., access terminal 210).System 1200 includes a logical grouping 1210 of electronic componentsthat can act in conjunction. In an aspect of the subject innovation,logical grouping 1210 includes an electronic component 1215 for encodinga first set of bits of information of a first communication channel in afirst modulation constellation; an electronic component 1225 forencoding a second set of bits of information of a second communicationchannel in a second modulation constellation; and an electroniccomponent 1235 for assigning a first weight to the first encodedconstellation and a second weight to the second encoded constellation togenerate a hierarchical modulation constellation through the combinationof the weighted first encoded constellation and the weighted secondencoded constellation. In addition, system 1200 can include electroniccomponent 1245 for modulating the first communication channel and thesecond communication channel in a common set of tones with thehierarchical modulation constellation, and a component 1255 forconveying the hierarchically modulated first communication channel andsecond communication channel.

System 1200 can also include a memory 1250 that retains instructions forexecuting functions associated with electrical components 1215, 1225,1235, 1245 and 1255, as well as measured or computed data that may begenerated during executing such functions. While shown as being externalto memory 1260, it is to be understood that one or more of electroniccomponents 1215, 1225, 1235, 1245, and 1255, and can exist within memory1260.

FIG. 13 illustrates a block diagram of an example system 1300 thatenables to decode hierarchically modulated channels in accordance withaspect described in the subject specification. System 1300 can reside,at least partially, within a mobile (e.g., access terminal 240). System1300 includes a logical grouping 1310 of electronic components that canact in conjunction. In an aspect of the subject innovation, logicalgrouping 1310 includes an electronic component 1315 for decoding a firstlayer of information bits of a first communication channel and a secondcommunication channel hierarchically modulated; and an electroniccomponent 1325 for decoding a second layer serially after decoding thefirst layer, wherein decoding the second layer includes means forcancelling soft symbols decoded in the first layer.

System 1300 can also include a memory 1330 that retains instructions forexecuting functions associated with electrical components 1315 and 1325,as well as measured or computed data that may be generated duringexecuting such functions. While shown as being external to memory 1330,it is to be understood that one or more of electronic components 1315and 1325, and can exist within memory 1330.

For a software implementation, the techniques described herein may beimplemented with modules (e.g., procedures, functions, and so on) thatperform the functions described herein. The software codes may be storedin memory units and executed by processors. The memory unit may beimplemented within the processor or external to the processor, in whichcase it can be communicatively coupled to the processor via variousmeans as is known in the art.

Various aspects or features described herein may be implemented as amethod, apparatus, or article of manufacture using standard programmingand/or engineering techniques. The term “article of manufacture” as usedherein is intended to encompass a computer program accessible from anycomputer-readable device, carrier, or media. For example,computer-readable media can include but are not limited to magneticstorage devices (e.g., hard disk, floppy disk, magnetic strips, etc.),optical disks (e.g., compact disk (CD), digital versatile disk (DVD),etc.), smart cards, and flash memory devices (e.g., EPROM, card, stick,key drive, etc.). Additionally, various storage media described hereincan represent one or more devices and/or other machine-readable mediafor storing information. The term “machine-readable medium” can include,without being limited to, wireless channels and various other mediacapable of storing, containing, and/or carrying instruction(s) and/ordata.

As it employed herein, the term “processor” can refer to a classicalarchitecture or a quantum computer. Classical architecture comprises,but is not limited to comprising, single-core processors;single-processors with software multithread execution capability;multi-core processors; multi-core processors with software multithreadexecution capability; multi-core processors with hardware multithreadtechnology; parallel platforms; and parallel platforms with distributedshared memory. Additionally, a processor can refer to an integratedcircuit, an application specific integrated circuit (ASIC), a digitalsignal processor (DSP), a field programmable gate array (FPGA), aprogrammable logic controller (PLC), a complex programmable logic device(CPLD), a discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. Quantum computer architecture may be based on qubitsembodied in gated or self-assembled quantum dots, nuclear magneticresonance platforms, superconducting Josephson junctions, etc.Processors can exploit nano-scale architectures such as, but not limitedto, molecular and quantum-dot based transistors, switches and gates, inorder to optimize space usage or enhance performance of user equipment.A processor may also be implemented as a combination of computingdevices, e.g., a combination of a DSP and a microprocessor, a pluralityof microprocessors, one or more microprocessors in conjunction with aDSP core, or any other such configuration.

Furthermore, in the subject specification, the term “memory” refers todata stores, algorithm stores, and other information stores such as, butnot limited to, image store, digital music and video store, charts anddatabases. It will be appreciated that the memory components describedherein can be either volatile memory or nonvolatile memory, or caninclude both volatile and nonvolatile memory. By way of illustration,and not limitation, nonvolatile memory can include read only memory(ROM), programmable ROM (PROM), electrically programmable ROM (EPROM),electrically erasable ROM (EEPROM), or flash memory. Volatile memory caninclude random access memory (RAM), which acts as external cache memory.By way of illustration and not limitation, RAM is available in manyforms such as synchronous RAM (SRAM), dynamic RAM (DRAM), synchronousDRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM(ESDRAM), Synchlink DRAM (SLDRAM), and direct Rambus RAM (DRRAM).Additionally, the disclosed memory components of systems and/or methodsherein are intended to comprise, without being limited to, these and anyother suitable types of memory.

What has been described above includes examples of one or moreembodiments. It is, of course, not possible to describe everyconceivable combination of components or methodologies for purposes ofdescribing the aforementioned embodiments, but one of ordinary skill inthe art may recognize that many further combinations and permutations ofvarious embodiments are possible. Accordingly, the described embodimentsare intended to embrace all such alterations, modifications andvariations that fall within the spirit and scope of the appended claims.Furthermore, to the extent that the term “includes” is used in eitherthe detailed description or the claims, such term is intended to beinclusive in a manner similar to the term “comprising” as “comprising”is interpreted when employed as a transitional word in a claim.

1. A method utilized in wireless communications, the method comprising:receiving a first communication channel and a second communicationchannel that are hierarchically modulated in a composed layer; whereinthe composed layer includes a first layer and a second layer; decodingthe first layer; and decoding the second layer via at least one of aserial decoding subsequent to decoding the first layer or a paralleldecoding concurrent with decoding the first layer.
 2. The method ofclaim 1, wherein a serial decoding subsequent to decoding the firstlayer includes cancelling soft symbols after decoding the first layer.3. The method of claim 2, wherein a hierarchic modulation constellationis a combination of a first constellation and a second constellation. 4.The method of claim 3, wherein the combination is a weightedsuperposition of the first constellation and the second constellation,wherein a first weight and a second weight are configurable.
 5. Themethod of claim 4, wherein the first communication channel is one of anACK (acknowledge) channel or a NACK (not-acknowledge) channel.
 6. Themethod of claim 3, wherein the second communication channel is a CQI(channel quality indication) channel
 7. An apparatus that operates in awireless communication system, the apparatus comprising: means fordecoding a first layer of information bits of a first communicationchannel and a second communication channel hierarchically modulated; andmeans for decoding a second layer serially after decoding the firstlayer, wherein decoding the second layer includes means for cancellingsoft symbols decoded in the first layer.
 8. The apparatus of claim 7,wherein means for decoding a first layer of information bits of a firstchannel and a second communication channel hierarchically modulatedincludes means for computing log-likelihood ratios on a set ofhierarchical constellation symbols.
 9. The apparatus of claim 7, whereinmeans for decoding a second layer serially after decoding a first layerincludes means for computing log-likelihood ratios on a subset ofhierarchical constellation symbols.
 10. The apparatus of claim 7,wherein a hierarchic modulation constellation is a combination of afirst constellation and a second constellation.
 11. The apparatus ofclaim 7, wherein the combination is a weighted superposition of thefirst constellation and the second constellation, wherein a first weightand a second weight are configurable.
 12. The apparatus of claim 7,wherein the first communication channel is one of an ACK (acknowledge)channel or a NACK (not-acknowledge) channel.
 13. The apparatus of claim7, wherein the second communication channel is a CQI (channel qualityindication) channel
 14. An electronic device that operates in a wirelessenvironment, the electronic device comprising: a processor configured todecode a first layer of information bits of a first communicationchannel and a second communication channel hierarchically modulated; andto decode a second layer serially after decoding the first layer,wherein decoding the second layer includes means for cancelling softsymbols decoded in the first layer; and a memory coupled to theprocessor.
 15. The electronic device of claim 14, to decode a firstlayer of information bits of a first channel and a second communicationchannel hierarchically modulated includes to computing log-likelihoodratios on a set of hierarchical constellation symbols.
 16. Theelectronic device of claim 15, wherein to decode a second layer seriallyafter decoding a first layer includes to compute log-likelihood ratioson a subset of hierarchical constellation symbols.
 17. The electronicdevice of claim 16, wherein a hierarchic modulation constellation is acombination of a first constellation and a second constellation.
 18. Theelectronic device of claim 17, wherein the combination is a weightedsuperposition of the first constellation and the second constellation,wherein a first weight and a second weight are configurable.
 19. Theelectronic device of claim 14, wherein the first communication channelis one of an ACK (acknowledge) channel or a NACK (not-acknowledge)channel.
 20. A computer program product comprising a computer-readablemedium including: code for causing at least one computer to receive afirst communication channel and a second communication channel that arehierarchically modulated in a composed layer; wherein the composed layerincludes a first layer and a second layer; code for causing at least onecomputer to decode the first layer; and code for causing at least onecomputer to decode the second layer via at least one of a serialdecoding subsequent to decoding the first layer or a parallel decodingconcurrent with decoding the first layer, wherein a serial decodingsubsequent to decoding the first layer includes cancelling soft symbolsafter decoding the first layer.
 21. The computer program product ofclaim 20, wherein a hierarchic modulation constellation is a combinationof a first constellation and a second constellation.
 22. The computerprogram product of claim 21, wherein the combination is a weightedsuperposition of the first constellation and the second constellation,wherein a first weight and a second weight are configurable.